The invention relates to a method and a device for cutting and/or cutting to length wound hoses. Additionally the invention relates to an appropriately produced wound hose.
Such metal hoses are called wound hoses, which are formed from windings of a metallic tape, with here the windings being connected to each other relatively loosely in a form-fitting fashion. Typical forms of the connection are hooked profiles (so-called LIH-liner) and folded profiles (agraffe-profile, so-called LIS-liner).
Wound hoses with a hooked profile are characterized in a particularly high flexibility. Wound hoses with folded profiles are relatively stiff in their entirety. Due to the high flexibility, particularly wound hoses with hooked profiles cannot easily be welded, because here no defined welded geometry develops.
A particularly preferred application of the above-mentioned wound hoses is conducting the gas of the exhaust system in passenger vehicles and utility vehicles. Additional applications are e.g., protective hoses for fiber optics, telephone lines, lines for measuring devices or alarm systems.
A particular problem is given in wound hoses in that they can unravel after being cut to length. Then they cannot be assembled any more or only with increased expense, which is undesired in production.
According to prior art, the above-mentioned wound hoses are sawed, e.g., by a melting saw, and then the loose end is fixed via a manually placed welding spot. This is labor extensive and accordingly expensive and thus less suitable for serial production. Additionally, particularly in the application of wound hoses in exhaust systems, the absence of particles is desired, which however can develop when a wound hose is sawed. Such particles or chips can destroy filters or other components arranged downstream, particularly components for exhaust treatment. Accordingly, increasingly laser cutting methods are used.
For this purpose, three axially off-set laser beams are used, guided circumferentially about the hose. A first and a second beam each place a circumferential seam in order to fix the material of the wound hose, with the two seams being arranged axially off-set.
Subsequently, via a third laser beam, cutting of the wound hose occurs between these two seams. Here, it has proven disadvantageous that the two seams are embodied relatively undefined on wound hoses, because a wound hose, due to its general design, as described above, shows only relatively little material and a relatively large clear space located therebetween. Here, the risk is given that during the attempt of forming a laser seam the wound hose is cut rather than fixed.
Additionally, in the above-mentioned method relatively large tolerances develop, due to the inherent mobility of the wound hose. In the past, this problem has resulted in cases, in which during the actual cutting process the third laser beam even damaged the previously generated seams themselves. Then, once more an unraveling of the wound hose occurs, at least aggravating any assembly.
German patent application 10 2012 214 044.1 discloses a generic method and/or a respective device, with here, in order to avoid the above-mentioned disadvantages, the wound hose is axially compressed in an area such that then a welding in this area can occur along a predetermined number of windings of the wound hose.